The present invention relates to an expansion nut, and more particularly to a one-piece expansion nut for the T-joint of pipes.
Referring to FIGS. 1A, 1B and 2, an expansion nut 2 according to the prior art is generally comprised of an internal thread 21 art the central hole thereof at either end thereof. The expanding pieces 3 are cut to form a plurality of tabs 31 extended radially and properly curved in the same direction, making their outer diameter slightly larger than the inner diameter 41 of one pipe 4. Both ends 22 of the nut 2 are made to allow the inner circle 32 of each expanding piece 3 to sit thereon, then these two ends 22 are hammered to make a tight fit between the inner circle 32 of each expanding piece 3 and the nut 2. When the nut 2 is put into the pipe 4 and a bolt 5 passes through another pipe 6 to screw onto the internal thread 21 of the nut 2, tabs 31 of the expanding pieces 3 can be expanded to complete a T-joint of the pipes.
For the expansion nut according to the prior art, however, the nut 2 and expanding pieces 3 must first be made separately, then have them assembled by many processing procedures. It is therefore complicated and inconvenient in its manufacture and assembly.